In most echinoderms ,

Options

A. mouth is on the lower side
B. mouth is on the upper side
C. anus is on the lower side
D. anus is on the ventral side

Answer

### Step-by-Step Solution:

1. **Understanding Echinoderms**: Echinoderms are a group of marine animals that include species like sea stars, sea urchins, and sea cucumbers. They have a unique body structure and symmetry.

2. **Identifying Body Surfaces**: Echinoderms have two main surfaces: the oral surface (where the mouth is located) and the aboral surface (the opposite side, often where the anus is located).

3. **Locating the Mouth**: In most echinoderms, the mouth is located on the oral surface, which is the lower side of the organism. For example, in sea urchins, the mouth is positioned on the underside.

4. **Locating the Anus**: The anus in echinoderms is typically found on the aboral surface, which is the upper side of the organism. This means that the anus is not on the lower side.

5. **Conclusion**: Based on the structure of echinoderms, we can conclude that the correct statement is that in most echinoderms, the mouth is on the lower side (oral surface).

### Final Answer:
In most echinoderms, the mouth is on the lower side.

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